The present invention relates to apparatus and methods used in the abatement of asbestos or similar materials containing particulate contaminants in a small work area. More particularly, the present invention relates to portable apparatus that allows spot abatement of asbestos or similar materials without significantly disrupting or disturbing other areas surrounding the small work area where the abatement is occurring. Additionally, the apparatus allows access above ceilings into contaminated areas for inspection and normal maintenance operations.
Asbestos is a naturally occurring, fibrous, magnesium silicate mineral that had, up until only a few years ago, been frequently used for thermal insulation. Asbestos exhibits remarkable thermal insulation and fire-proofing properties. Unfortunately, air-borne fibers and other particles of asbestos have proven to be a major lung irritant capable of causing the serious and debilitating disease known as asbestosis among chronically exposed workers, as well as a type of cancer known as mesothelioma.
As a result of the potential health hazard associated with handling asbestos, or similar materials that include particulate contaminants, there has been in recent years a concerted effort to remove or abate asbestos from or in buildings or other structures that have utilized asbestos as an insulating material. Many regulations have been adopted and are in place to ensure the safety of workers who remove asbestos, or other personnel in the vicinity of a work area where asbestos removal is occurring, as well as to ensure that the asbestos being removed is not introduced into the surrounding atmosphere.
U.S. Pat. No. 4,604,111, for example, describes a fairly common system which is employed in an asbestos removal project. As described in the '111 patent, and as is commonly practiced, before asbestos can be removed, an enclosure must be created around the space in which the asbestos is to be removed. The space is sealed by means of plastic sheets or the like. An air inlet is provided for the enclosed space to permit air to be drawn thereinto. A suitable filtration unit is then employed that provides an air outlet. The air outlet of the filtration unit is placed in communication with the area outside of the enclosed space. A blower, or equivalent device, is provided in the filtration unit so that the contaminated air in the enclosed space is drawn through the filtration unit with the asbestos fibers being collected in the filtration unit. In this way, the filtration unit creates a "negative air system" that assures that all of the air in the enclosed space is under pressure to leave the enclosed space. As the air can only leave through the air outlet, all of the air must thus pass through the filtration unit, where the dangerous asbestos fibers are collected.
When the health hazards associated with asbestos materials were first identified, there was an intensive effort to remove all asbestos-containing materials from any buildings or other structures where the asbestos was found to exist. Such efforts proved to be very expensive and labor-intensive, and (with the benefit of hindsight) an over-reaction to a problem that could be addressed through simpler and less expensive means. As a less-expensive alternative to asbestos removal, for example, it was discovered that an effective asbestos monitoring and maintenance program could achieve the same desired goal --preventing the hazardous asbestos fibers from becoming airborne and coming in contact with any personnel within or around the structure where the asbestos materials have been used. Asbestos monitoring and maintenance thus involves sealing or encapsulating the asbestos material in a suitable film, e.g., by spraying or otherwise coating the asbestos materials with an appropriate encapsulating substance (termed an "encapsulant"). The resulting film, or equivalent sealer or encapsulant, in combination with the structure wherein the asbestos is located (e.g., the ceiling or walls) thus effectively encapsulates the asbestos fibers and prevents them from becoming airborne. Hence, asbestos monitoring, maintenance and encapsulation procedures (AMMEP) advantageously allow the health hazard associated with the presence of asbestos to be minimized, at a much reduced cost over asbestos removal. Further, such AMMEP avoid the problems of handling and disposing the asbestos materials, which problems are always present whenever asbestos materials are removed. AMMEP further offer the advantage of allowing the asbestos materials to continue to provide their insulating and fireproofing properties. Hence, AMMEP (as opposed to asbestos removal) has proven to be a preferred approach for dealing with the hazardous asbestos materials that were commonly used in the building and construction industry prior to about 1978, before asbestos was known to pose any health hazard.
Unfortunately, AMMEP does not eliminate all health concerns. It is sometimes necessary to do remodeling or other construction modifications in a building or structure wherein AMMEP have been and are being utilized. When such remodeling or other construction modifications are necessary, the same care must be exercised as is used during asbestos removal, even though the area affected by the remodeling or construction modification may comprise only a small area or "spot" of the overall area within a building.
Heretofore, when spot entry into areas containing asbestos materials has been required, e.g., to do remodeling, to retrofit sprinkler or electrical systems, or to perform other modifications, one of two approaches would be pursued. A first approach requires the entire evacuation of the overall work area wherein the work is to be performed, e.g., an entire floor, or an entire building, with a suitable enclosure and negative air pressure system being established for the overall work area. This approach is very disruptive to the occupants of the work area, as they must completely evacuate the area while the work is being performed, even though only small areas of the overall work area are affected by the actual work. However, depending upon the number of small work areas that are to be involved, this approach is still frequently used.
A second approach requires the evacuation of just the immediate area surrounding the structure where the spot entry is to be made. A suitable enclosure is erected around the small area and a negative air pressure system is established within the enclosure. The enclosure must seal off the area to be affected, from finished floor to finished ceiling, and is typically realized using polyethylene sheeting, supported by appropriate scaffolding support structure. While this approach avoids the necessity of evacuating the entire overall area, as is required with the first approach described above, it requires continual erection and disassembly of the enclosure structure around each spot area where the work is to be performed. Thus, when the retrofit or other work is finished in one area, and further retrofit or work is required in another area, it is necessary to disassemble and take down the enclosure structure, move to the next work area, and seal the new area in the same manner. Disadvantageously, this approach takes a great amount of time and materials, thereby making spot retrofit or remodeling work in an area having asbestos materials very labor intensive.
U.S. Pat. No. 4,682,448 describes a system designed to minimize some of the labor-intensive aspects of this second approach. Disclosed in the '448 patent is a system that includes a work cubical that is erected on a mobile base. The walls of the cubical are made from a flexible material that includes zippers to allow entry of work personnel thereinto. An external filtration and pump unit is then connected to the system to establish a negative air system. Thus, the cubical can be moved from one spot to another within the same general area without disassembly, so long as the cubical does not need to pass through a low door, and so long as the external filtration unit is connected to the cubical at each work location. However, disassembly is still required when the cubical is moved through low doorways, and the external filtration unit must be disconnected and reconnected each time the cubical is moved. Further, in the event of a major "falldown" of asbestos materials into the cubical, as sometimes occurs when performing remodeling or inspection in a contaminated area, there is no easy way to transfer the cubical, and the personnel inside of the cubical, to a "clean room" or large decontamination area. Rather, the personnel must exit the cubical, thereby causing a potential release of contaminating fibers into the surrounding area.
In view of the above, it is evident that what is needed is a system for performing spot abatement of asbestos, including asbestos monitoring, maintenance, and encapsulation procedures, that provides all the safety precautions commonly utilized when working with or handling asbestos materials, e.g., creating a negative air pressure region around a given work site, without the disruptive effects experienced using the first approach described above, and without the time consuming, labor-intensive disassembly and reassembly tasks of the second approach described above. Further, what is needed is a system that can handle asbestos "falldown", should it occur, in a safe and effective manner. The present invention advantageously addresses these and other needs.